ZyXEL Communications Prestige 2602R Series, User Manual

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Prestige 2602R Series User’s Guide
Chapter 5 WAN Setup 81
5.1.4.2 IP Assignment with RFC 1483 Encapsulation
In this case the IP Address Assignment must be static with the same requirements for the IP
Address and ENET ENCAP Gateway fields as stated above.
5.1.4.3 IP Assignment with ENET ENCAP Encapsulation
In this case you can have either a static or dynamic IP. For a static IP you must fill in all the IP
Address and ENET ENCAP Gateway fields as supplied by your ISP. However for a
dynamic IP, the Prestige acts as a DHCP client on the WAN port and so the IP Address and
ENET ENCAP Gateway fields are not applicable (N/A) as the DHCP server assigns them to
the Prestige.
5.1.5 Nailed-Up Connection (PPP)
A nailed-up connection is a dial-up line where the connection is always up regardless of traffic
demand. The Prestige does two things when you specify a nailed-up connection. The first is
that idle timeout is disabled. The second is that the Prestige will try to bring up the connection
when turned on and whenever the connection is down. A nailed-up connection can be very
expensive for obvious reasons.
Do not specify a nailed-up connection unless your telephone company offers flat-rate service
or you need a constant connection and the cost is of no concern
5.2 Metric
The metric represents the "cost of transmission". A router determines the best route for
transmission by choosing a path with the lowest "cost". RIP routing uses hop count as the
measurement of cost, with a minimum of "1" for directly connected networks. The number
must be between "1" and "15"; a number greater than "15" means the link is down. The
smaller the number, the lower the "cost".
The metric sets the priority for the Prestige’s routes to the Internet. If any two of the default
routes have the same metric, the Prestige uses the following pre-defined priorities:
• Normal route: designated by the ISP (see Section 5.6 on page 83 )
• Traffic-redirect route (see Section 5.7 on page 86 )
For example, if the normal route has a metric of "1" and the traffic-redirect route has a metric
of "2" and dial-backup route has a metric of "3", then the normal route acts as the primary
default route. If the normal route fails to connect to the Internet, the Prestige tries the traffic-
redirect route next. In the same manner, the Prestige uses the dial-backup route if the traffic-
redirect route also fails.
If you want the dial-backup route to take first priority over the traffic-redirect route or even the
normal route, all you need to do is set the dial-backup route’s metric to "1" and the others to
"2" (or greater).